Cell viability of retinal photoreceptor evaluated by polar distribution of Ca(2+) and electrical charge

The polar organisation is characteristic to the living cell and disappears with the cell functional decay. Here we report experimental evidence that frog retinal photoreceptor rod cell shows a polar distribution of the electrical charge and of free cytosolic Ca(2+) along its length. Retinal rod cells were loaded with Calcium sensitive dye (Green1) and examined under fluorescence microscopy coupled with an image analysis system. In addition, suspension of rod cells was placed in direct current electric field for electrical polarity assessment. Both polar Ca(2+) and electrical charge distribution can be objectively measured and quantified providing thus a fine test for cell viability. Such a test is required in checking the functional integrity of photoreceptors used in retinal transplant.